1. Field of the Invention
This invention relates to a method of regenerating basic hydrogen peroxide (BHP) that has been depleted in a chemical system, particularly regenerating BHP in a plant scale operation.
2. The Prior Art
Basic hydrogen peroxide (BHP) is the principle fuel for Chemical Oxgygen-Iodine Lasers (COIL). COIL systems have market potential for both military and industrial applications in that such systems output a powerful laser beam of high quality useful, e.g. in cutting and welding metals.
Such COIL systems as noted above, require BHP as a principle energy source. In the prior art BHP has been generated by reacting aqueous potassium hydroxide with aqueous hydrogen peroxide in an agitated, cooled vessel. The reactive species in BHP that results from this acid/base reaction is the hydroperoxide ion, O.sub.2 H.sup.-, the conjugate base of hydrogen peroxide: EQU KOH(aq)+H.sub.2 O.sub.2 (aq).fwdarw.K.sup.+ (aq)+O.sub.2 H.sup.- (aq)+H.sub.2 O (1)
This solution is then passed through another reactor to form singlet delta oxygen O.sub.2(.sup.1 .DELTA.) from chlorine gas. Hydroperoxide ions are consumed in this singlet oxygen generator (SOG) according to the following reaction: EQU Cl.sub.2 +2O.sub.2 H.sup.- (aq)+2K.sup.+ (aq).fwdarw.O.sub.2 (.sup.1 .DELTA.)+H.sub.2 O.sub.2 (aq)+2KCl(s) (2)
BHP is generally not regenerated during laser operations, but is, instead, run batchwise until the hydroperoxide concentration is too low or the potassium chloride (KCl) concentration is too high to support lasing. The spent BHP is then discarded. At this point, only 50 mole percent of the reactive species, O.sub.2 H.sup.-, has been consumed which corresponds to approximately 8 percent of the total fuel weight.
Under normal operating conditions, the run time of the laser is extended by producing the largest amount of BHP possible and flowing it through the SOG. These large Volumes of BHP simply extend the run time of COILs and do not address the problem of regenerating the fuel. As a result, large quantitites of the reactive hydroperoxide ion are wasted when the solution is finally discarded.
What is needed is a process for regenerating depleted BHP solution to avoid the above waste thereof, as well as excessively large BHP storage systems that would otherwise be required.
Also in the prior art, such regeneration of depleted BHP solution has been accomplished in the laboratory, see U.S. Pat. No. 5,378,449 to Dinges et al. (1995), which patent is incorporated herein by reference.
Such reference discloses a method for regenerating BHP by reacting KO.sub.2 with an acid selected from the group consisting of H.sub.2 O.sub.2 and a protic acid. Thus such reaction can be carried out according to: EQU 2KO.sub.2 (s)+H.sub.2 O.sub.2 (aq).fwdarw.2O.sub.2 H.sup.- (aq)+O.sub.2 +2K.sup.+ (aq) (3)
Thus reaction (3) regenerates BHP for use in reaction (2) above so as to evolve the singlet delta oxygen of reaction (2) used in COIL lasing. Such reactions are preferably conducted at 0.degree. to -10.degree. C. and the BHP product is desirably stored at about -20.degree. C. for stability purposes.
Now when the BHP reaction (2) is depleted, KO.sub.2 can be added to the BHP/H.sub.2 O.sub.2 solution to react with the H.sub.2 O.sub.2 of reaction (2) to regenerate BHP per reaction (3) hereof.
The KO.sub.2 solid is reacted with dilute H.sub.2 O.sub.2 (e.g. 10 to 30 wt. % and preferably 15 to 20 wt. % H.sub.2 O.sub.2 in H.sub.2 O) in the (depleted) BHP solution per reactions (2) and (3) as discussed above. The KO.sub.2 thus consumes one equivalent of hydrogen peroxide and produces 2 equivalents of hydroperoxide ion (BHP), thus reversing the chlorine/BHP reaction (2) that evolves singlet delta oxygen, the energetic species in the COIL system. That is, as indicated above, reaction (3) reverses the chemical process of the chlorine/BHP reaction (2) above, with respect to the O.sub.2 H.sup.- (BHP) and H.sub.2 O.sub.2 components. The liberation of oxygen in reaction (3) above, impedes reversibility, and encourages the completeness of the reaction. Hence, the KO.sub.2 /H.sub.2 O.sub.2 reaction can be used to regenerate BHP that has been depleted through normal COIL operation. For a complete regeneration process, however, the Potassium Chloride salt, KCl must be physically removed from the BHP solution and make-up H.sub.2 O.sub.2 can be added per the invention. Accordingly, the above process is a prior art process requiring periodic removal of KCl and periodic addition of KO.sub.2 (or KOH) along with aqueous H.sub.2 O.sub.2. The above steps are necessary in the above BHP regeneration process and have been impediments to converting the above laboratory process to a continuous BHP regeneration process for use on a commercial or plant size scale.
Thus, it is believed that the above laboratory scale process has not previously been converted to a process that could continuously regenerate depleted BHP on a commercial scale from, e.g. the process of reaction (2) above.
That is, the above prior art laboratory processes are batch-type processes in which KCl is filtered out of the depleted BHP solution and then KO.sub.2 solids (or KOH pellets) and aqueous H.sub.2 O.sub.2 are added to the filtered batch of depleted BHP solution to regenerate BHP solution, as described above. Again such steps constitute a batch process and a continuous BHP regeneration process suitable for commercial use, has not yet been seen in the prior art.
Accordingly, there is need and market for an improved BHP regeneration process that Significantly overcomes the above pior art shortcomings.
There has now been discovered a method for continuous regeneration of BHP suitable for use in a commercial or plant-size scale.